This invention is an improved voltage-to-frequency (V/F) convertor. In particular, it is a V/F convertor that uses a single precision frequency source to provide accuracy over a relatively wide range of input voltages for a plurality of V/F measurements.
Measurements of energy, power, reactive volt-amperes (VARs) and VAR-hours call for a high degree of accuracy of measurements over a wide range of input values. Various means have been used to obtain a voltage that is proportional either to power or reactive volt-amperes. One such means is shown in U.S. Pat. No. 4,498,138 entitled "Electronic Watt/Var Transducer", which is incorporated here by reference as if set forth fully.
In a particular application it was desirable to provide indications of watt-hour activity on three separate power systems. A voltage proportional to the power level in each of the systems was available for use. Each of these signals needed some form of time integration to provide a measure of the energy consumed in units of watt-hours. A system being monitored might operate at full power or at a very low power level, but the measurement needed to be made with the same accuracy for each.
Although the system in question called for monitoring of three channels, it may become desirable to add more channels at minimum expense.